Present-day microwave electric field (E-field) measurement probes are undesirably large (greater than 1.5 mm.), are not linear over a larger range of microwave power values, and do not have antenna patterns which are independent of the lead structure. Accordingly, such present-day measurement probes are burdened by inflexibility, in terms of the applications to which they may be put, and also yield results which are undesirably inaccurate. In addition, measuring probes of the prior art are quite sensitive to stray radiation and noise, and this leads to measurement results which are further distorted and inaccurate.
Typical among measurement probes of the prior art is the microwave leakage detector disclosed in Newman--U.S. Pat. No. 4,338,595. The microwave leakage detector disclosed therein comprises a dipole antenna having arms or sections, with a diode inserted between the respective arms or sections. In the arrangement of Newman, leads connect respective sides of the diode to a light-emitting diode. It is stated that the detector disclosed in this patent can be utilized to determine whether a microwave oven, or any other device, is leaking radiation beyond the limits imposed by the Food and Drug Administration.
Nevertheless, the microwave leakage detector disclosed in the aforementioned patent does not have the flexibility which would permit it to be used not only for determining whether a microwave oven, or any other device, is leaking radiation beyond prescribed limits, but also for in vivo measurement of RF fields during the treatment of tumors by diathermy, and other similar medical applications, as well as other applications in general. Furthermore, the microwave leakage detector disclosed in the aforementioned patent is burdened by some of the other disadvantages of arrangements of the prior art, as described above.
Other arrangements of the prior art which are of general background interest with respect to the development of electromagnetic field measurement probes are described in the following U.S. patents: Carney--U.S. Pat. No. 3,460,528; Brown et al--U.S. Pat. No. 3,555,529; Jacobi et al--U.S. Pat. No. 4,162,500; Aaby et al--U.S. Pat. No. 4,344,440; Lamb--U.S. Pat. No. 2,517,325; Richardson--U.S. Pat. No. 3,063,010; Berman--U.S. Pat. No. 2,321,356; and Wing--U.S. Pat. No. 2,436,538.
The following publications are also generally pertinent relative to field measurement probe arrangements of the prior art:
(1) Bassen, H. "A Broad-band Miniature Isotropic Electric Field Measurement System", in 1975 IEEE Electromagnetic Compatibility Symp. Rec., IEEE Publ. 75 CH1002-5 EMC, pp. 5BIIa (1-5), October 1975.
(2) Bassen, H., Swicord, M., Abita, J. "A Miniature, Broadband Electric Field Probe". Ann NY Acad Sci 247:481-486 (February 1975).
(3) Bassen, H. "Internal Dosimetry and External Microwave Field Measurements Using Miniature Electric Field Probes," Symposium on Biological Effects and Measurements of Radio Frequency/Microwaves, HEW Publication (FDA) 77-8026, July 1977, pp. 136-151.
(4) Green, F. "Development of Electric and Magnetic Near Field Probes," NBS Tech. Note 658, January 1975.
(5) Kanda, M., Riese, F. X., and Belsher, D.R. "A Broadband, Isotropic, Real-Time, Electric-Field Sensor (BIRES) Using Resistively Loaded Dipoles," NBSIR 79-1622, (U.S.), National Bureau of Standards, December 1979.
(6) Kanda, M. "The Characteristics of Broadband, Isotropic, Electric-Field and Magnetic-Field Probes," NBSIR 77-868 (U.S.), National Bureau of Standards, November 1977.
(7) Kanda, M., and Ries, F.X. "Dipole-Based EM Probe Grabs Complex Fields," Microwaves, January 1981, pp. 63-66.